You are going to get different answers on this it's all based on buyer preference. I love the V8 exhaust note, wasn't impressed with the 3.5i off the line (tranny would hunt or some kind of delay), the MPG is negligible between the two and I couldn't live with the little round tailpipes on the 3.5i. On top of that I keep my cars 7-10 years and I would rather go with a naturally-aspirated engine for reliability reasons. My $.02.

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2008 X5 4.8
Jet Black/Black Nevada/Dark Burl Walnut
Adaptive Drive
Premium Pack
Tech Pack
Climate Pack
Sport Pack
20" Wheel Option
Premium Sound
Sirius Satellite
Rear DVD Entertainment
Multi-Contour Seats
Comfort Access
3rd Row Seat
Heated Front Seats
Running Boards
3M VentureShield Paint Protection Film